Patent GB-729135-A (GB)
Title: Improvements in or relating to method of decorating ceramic bodies and the ceramic bodies resulting from said method
IPC: B28B11/04
Filed: 1952-03-06
Abstract: 729,135. Glazes. CERATILE CORPORATION. March 6, 1952, No. 5872/52. Drawings to Specification. Class 56. Ceramic clay articles are decorated by applying a design alumina-containing glaze-forming composition to selected portions of a surface of an article, the design composition having sufficient solids to form a uniform layer of solids of a thickness of from 3 to 30 thousandths of an inch before firing, thereafter applying a continuous layer of a background glaze-forming composition containing alumina over the portions coated by the design composition and the uncoated portions of the surface, the background composition having sufficient solids to form a uniform layer of solids of a thickness of from 5 to 25 thousandths of an inch before firing, and glost firing the design and background compositions on the article; the design and background compositions are from the following groups of glazes : (1) a lead-silicate glaze consisting essentially of substantial proportions of lead oxide and silica; (2) a leadboro-silicate glaze consisting essentially of substantial proportions of lead oxide, boron oxide and silica; (3) an alkali-boro-silicate glaze consisting essentially of substantial proportions of alkali metal oxides, boron oxide and silica and (4) an alkali-lime-silicate,glaze consisting essentially of substantial proportions of alkali metal oxides, calcium oxide and silica, the two compositions being chosen from different groups and such that during glost firing the background composition developes a less-fluid state than the design composition and withdraws therefrom without substantial diffusion thereinto to free the design composition on the selected portions of the surface, both compositions maturing in the same or overlapping temperature ranges and the glost firing being carried out within these ranges. The design composition may contain ceramic pigmenting materials and the background composition opacifying materials. The viscosity of the glazes may be controlled by the alumina content thereof or may be increased or decreased by the addition of refractory oxides such as magnesium oxide, calcium oxide or fluxing oxides respectively. The following examples of pairs of design and background glazes are given, the composition being expressed in parts by weight: Design glaze: potash feldspar 11.8; china clay 5.7; alumina (Al 2 O 3 ) 3.3; copper carbonate 4.1; iron oxide (Fe 2 O 3 ) 4.1; boric oxide 10.0; tin oxide (SnO 2 ) 11.5; frit A (below) 9.8; frit B 40.4. Background glaze: feldspar 12.1; silica 6.7; zinc oxide 3.2; china clay 4.0; frit C (below) 64.5; frit D (below) 4.0; zirconium oxide 5.3. Design glaze : frit B (below) 88.3; stain 11.7. Background glaze: china clay 13.4; stain 0.2; frit E (below) 36.4; frit F (below) 33.8; opacifier A (below) 2.7; opacifier B (below) 13.4. Design glaze: china clay 12.2; potash feldspar 8.2; silica 13.5; zinc oxide 7.4; white lead 2.0; copper carbonate 4.8; frit A (below 23.8; opacifier B (below) 10.0. Background glaze: potash feldspar 30.5; silica 9.7; china clay 9.0; whiting 7.1; zinc oxide 9.3; frit A (below) 19.0; opacifier B (below) 15.4. The frits and opacifiers indicated above have the following compositions, expressed in parts by weight: Frit A: sodium potassium oxide 10.4; calcium oxide 20.2; boric oxide 23.3; silica 46.2. Frit B: sodium oxide 0.4; potassium oxide 1.3; lead oxide (PbO) 67.8; alumina 4.8; silica 28.1. Frit C : sodium potassium oxide 21.67; zinc  oxide 3.60; alumina 9.13; boric oxide 13.00; antimony oxide (Sb 2 O 3 ) 3.98; silica 45.2. Frit D: sodium potassium oxide 17.72; sodium fluoride 3.49; zinc oxide 0.98; alumina 12.82; boric oxide 16.77; silica 46.15. Frit E : sodium oxide 6.1; lead oxide (PbO) 44.4; boric oxide 13.9; silica 35.6. Frit F : lead oxide (PbO) 63.2; boric oxide 19.8; silica 17.0. Opacifier A: zirconium oxide 89.88; silica 7.20; alumina 1.5; sodium oxide 1.3. Opacifier B: zirconium oxide 65.82; silica 33.56.